Spacebar Thumbedness: Which Thumb Do You Use?

I use the left thumb for typing on the spacebar (up to 140 WPM because beyond that a lot of conventional keyswitches break down), which happens to be in the minority for typing as generally the right thumb is used. It's 'correct' to use either thumb for typing but generally the right thumb is favoured.

Which begs the question... why would someone use the left thumb for typing subconsciously? While I was exposed to a lot of typing programs as a kid, I never really paid much attention to them and just naturally ended up learning to type on my own as I used my computer more. Some of my typing habits are considered 'bad' but they don't hinder typing speed at all. In some instances I could acutally create an argument for how some of my habits actually benefit fast typing... but anyways.

The Influence of Old DOS & PC Games

I posed the question to my cousin one random day, and he said: "hey I use the left thumb as well for typing!" but wasn't aware that the right thumb was generally the consensus for typing. And to be perfectly fair it's kind of an odd thing to question.

After a little brainstorming he figured it out! It's because of old PC games where a lot of the key combinations used Ctrl / Alt / Shift / Spacebar on the left side, and you use the arrow keys with your right hand.

I'm not sure why it wasn't blatantly obvious to me, but that's totally the case: because we were already using our left thumbs for the spacebar in games it just naturally carried over into regular typing. So there you have it, if you use the left thumb for the spacebar you're probably an old PC gamer, RIP.